MODIFYING OF GLOBAL-CELL MODEL OF 3-D AND 4-STEP BRAIDED COMPOSITES

A cross model of 3-D braided composites is presented based on elastic theory. The model is simple and programmed easily. Modulus is calculated easily, but certain error exists in results. The author summarizes the factors which affect the elastic modulus of 3-D braided composites and the cross model of the composites is modified twice firstly. The reasons and results of the model modified are different. Firstly, the traditional global-cell model of unilateral composites is modified. Based on this, the model is modified secondly considering the fiber curve radian of fabric structures. And fiber's curve radian is simulated by sinusoid. Using the cross model modified and MATLAB software, the composites modulus and stress on a fiber section at tensile load are calculated. The predicted results of the modulus based on the cross model modified twice are in good agreement with experiments results. The 3-D braided composites mechanism of fracture is interpreted by stress results.